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inrrl  l 


and 


Soldering 


BY  JAMES  F.  HOBAKT 


T     T     T 


razng. 

Soldering  and  brazing  are  terms  often  used  to  de- 
note the  same  operation,  that  of  joining  similar  or  dis- 
similar metals  by  means  of  molten  metal  which  may  be 
of  the  same  kind,  but  which  usually  has  a  lower  melting 
point  than  the  metals  to  be  joined.  The  term  "brazing" 
is  usually  employed  to  denote  the  soldering  with  an  alloy 
of  copper  or  zinc.  "Soldering"  is  usually  taken  to  repre- 
sent the  joining  of  surfaces  by  means  of  an  alloy  of  lead 
and  tin,  and  "hard-soldering"  is  understood  to  mean  the 
process  of  uniting  as  above  described  with  silver  and  its 
alloys  used  as  a  uniting  metal.  Hard  soldering  and  braz- 
ing are  practically  the  same,  and  are  both  done  in  about 
the  same  way. 

The  theory  of  brazing  is  the  melting  of  a^ow  fusing 
metal  against  the  metals  to  be  united  while  they  are  in 
such  a  condition  of  cleanliness  and  temperature  that  the 
metal  welds  itself  to  them.  Soft  brass,  when  melted,  will 
weld  itself  to  iron,  copper,  and  a  number  of  other  metals, 
while  the  temperature  of  the  metals  in  question  is  at  a  con- 
siderable number  of  degrees  below  their  several  melting 
points.  In  fact,  only  heat  enough  need  be  employed  to 
fairly  melt  the  uniting  metal  and  to  render  it  fluid  enough 
to  flow,  or  to  "run,"  as  the  mechanic  aptly  states  it. 

To  braze,  also  to  solder,  it  is  absolutely  necessary  that 
the  surfaces  to  be  united  are  clean  and  free  from  oxide. 


Copyright  1906.  The  Derry-Collard  Oo. 


Brazing. 

The  term  "clean"  is  used  in  brazing  and  soldering,  to 
mean  that  there  is  no  "matter  in  the  wrong  place"  as  far 
as  the  surfaces  to  be  operated  upon  are  concerned.  If  the 
surfaces  should  be  covered  with  a  mixture  of -plumbago 
and  soap,  it  is  pretty  sure  that  the  brass  would  not  adhere, 
and  they  could  be  called  "dirty."  If,  on  the  contrary,  the 
surfaces  were  daubed  with  grease,  resin,  lime,  borax  or 
similar  substances,  the  brazing  will  not  be  interfered  with  ; 
hence,  it  is  better  to  say  that  surfaces  to  be  brazed  or 
soldered,  should  be  made  bright  and  free  from  oxide, 
finger  marks,  and  all  other  matter  except  the  proper  flux 
to  prevent  oxidization  of  the  surfaces  when  heated.  This, 
and  this  alone,  is  the  purpose  of  all  the  fluxes  used  either 
in  soldering,  brazing  or  welding.  The  flux  prevents  ox- 
idization from  contact  of  the  hot  metal  with  the  air,  or 
with  the  gases  from  the  fuel  used  in  heating. 

Aside  from  the  proper  cleaning  and  fluxing  of  metals 
to  be  brazed  or  soldered,  it  is  necessary  that  they  be  fitted 
together  as  closely  as  possible.  It  may  seem  like  a  par- 
adox, but  is  the  truth  never  the  less,  that  when  surfaces 
are  united  by  brazing,  the  union  is  stronger  the  less  brass 
there  is  between  the  surfaces.  That  is :  The  closer  the  fit- 
ting of  the  parts,  the  stronger  will  the  braze  be  after  com- 
pletion. It  is  unnecessary  to  "leave  space  for  the  brass," 
in  fitting  for  a  brazed  joint.  The  penetrating  power  of 
melted  brass  may  be  demonstrated  by  drilling  a  hole  in  a 
piece  of  iron  or  steel.  Drive  a  plug  in  the  drilled  hole,  and 
force  it  in  as  tightly  as  possible,  then  rivet  the  ends  of  the 
plug  and  proceed  to  braze  around  one  end  of  it,  when  it 
will  be  found  upon  test,  that  no  matter  how  tightly  the 
plug  may  have  been  driven  in,  the  melted  brass  has  found 
its  way  through  the  plate  beside  and  around  the  riveted 
plug,  and  that  it  has  brazed  both  ends  of  the  plug  and  its 


Brazing. 


rre  length  as  well.  Therefore,  fit  tight,  for  brazing, 
an  i  trust  the  liquid  brass  to  find  its  way  through  the 
entire  joint  without  fail. 

Borax  is  the  flux  usually  employed  for  all  kinds  of 
brazing.  For  commercial  work  on  a  large  scale,  boracic 
acid  is  used  as  it  is  cheaper  than  borax,  being  purchased 
in  a  granular  form,  in  bulk,  by  the  keg  or  barrel.  For 
the  uniting  metal,  some  alloy  of  copper  and  zinc  is  uni-( 
versally  employed.  When  other  substances,  such  as  silver 
is  used,  the  operation  becomes  known  as  "hard  soldering," 
as  described  elsewhere. 

The  particular  alloy  used  for  brazing,  is  called  "spel- 
ter," and  consists  of  equal  parts  of  copper  and  zinc.  For 
different  operations  it  is  necessary  to  use  either  a  harder 
or  softer  alloy,  hence  the  proportions  of  metals  vary  in  the 
alloy  according  to  the  following  table : 


Brazing  Alloys. 

Tin. 

Copper. 

Zinc. 

Antimony 

Hardest, 
Hard  (spelter) 
Soft, 
Softest, 

o 
o 

3 
i 

4 
o 

i 
i 

3 
o 

o 
o 
o 
I 

In  a  number  of  dictionaries,  the  proper  metal  for 
brazing  is  given  as  "Fine  Brass,  one  part ;  Zinc,  one  part." 
This  means  that  the  copper  in  the  brass  receives  another 
portion  of  zinc,  thus  making  the  alloy  softer  and  lowering 
the  melting  point. 

In  commercial  brazing,  it  is"  frequently  profitable  to 
mix  the  spelter  with  the  proper  proportion  of  boracic  acid 
as  found  by  experiment  to  be  necessary.  Then,  the  mix- 
ture is  placed  over  or  upon  the  parts  to  be  brazed,  and 
subjected  to  heat  sufficient  to  melt  the  brass.  As  soon  as 
the  brass  is  seen  to  flow,  "run,"  the  workman  calls  it,  the 


Brazing. 

article  is  removed  from  the  fire  and  the  surface — if  it  will 
allow — is  rubbed  or  scraped  with  a  piece  of  metal  or  with 
a  scratch  brush  to  remove  the  flux  and  a  portion  of  the 
superfluous  brass.  In  many  cases  the  scraping  can  not  be 
permitted  owing  to  the  nature  of  the  work,  but  whenever 
possible,  it  should  be  done  as  the  flux  comes  off  much 
easier  when  hot  than  after  it  gets  cold. 

The  manner  of  applying  *he  spelter  and  borax  also 
differs  with  the  work  to  be  done.  When  a  plain  ring  is  to 
be  brazed,  it  is  sufficient  to  hang  the  ring  on  the  end  of  a 
wire  or  a  rod  of  iron  and  place  a  bit  of  spelter  and  borax 
inside  the  ring  which  has  been  placed  so  that  'the  part 
to  be  brazed  is  downward.  Usually  the  spelter  and  borax 
can  be  deposited  in  some  angle  of  the  work,  or,  upon 
some  flat  surface  which  will  keep  it  in  place  during  the 
heating  operation.  Sometimes,  however,  this  is  impos- 
sible, as  in  brazing  a  wire.  In  such  cases,  select  a  bit  of 
spelter  which  is  long  enough  to -bend  up  U-shaped  so  it 
could  be  hung  over  the  wire.  The  borax  can  readily  be 
made  to  adhere  by  warming  the  wire. 

It  is  best  to  heat  rather  slowly,  in  order  that  the  joint 
may  be  brought  to  a  dull  red  heat  without  burning  any 
portion,  or  without  any  part  remaining  too  cold.  When 
the  heat  is  forced  so  that  one  portion  of  the  metal  is  hot 
enough  to  mdt  the  spelter  that  happens  to  be  on  it,  while 
another  part  of  the  joint  is  below  the  melting  part  of 
spelter,  there  is  little  possibility  of  securing  a  perfect 
joint.  Heating  evenly  is  absolutely  necessary.  It  must 
be  insisted  upon  or  there  will  be  no  good  work  done  in 
brazing. 

Brazing  can  be  done  with  any  source  of  heat  which 
will  melt  the  spelter,  but  a  properly  arranged  gas  flame 
is  the  best  that  can  be  provided.  The  writer  has  more 


Brazing. 

than  once  done  work  in  an  excellent  manner  in  a  pile  of 
coals  in  an  open  fireplace  with  the  hand-bellows  as  a 
source  of  air  pressure.  Indeed,  upon  one  occasion,  in  a 
hunter's  camp,  a  hatchet,  split  through  the  poll  to  the 
very  eye,  was  successfully  brazed  with  a  bit  of  soft  brass 
wire  used  for  snaring  fish.  The  flux  was  a  bit  of  borax 
from  the  medicine  chest,  and  the  brass  melting  fire  was  a 
kettle  full  of  coals  set  jrtst  inside  the  camp  door  and 
banked  with  wet  clay  to  approximate  a  smith's  forge.  The 
necessary  blast  was  supplied  by  a  cone  of  birch  bark,  the 
large  end  of  which  was  daubed  with  clay  tightly  into  a 
hole  in  the  wall  of  the  camp.  The  small  end  of  the  cone 
led  into  a  little  clay  passage  which  conducted  the  wind 
pressure  into  the  bed  of  coals.  No  better  working  outfit 
couM  be  desired  for  the  limited  work  to  be  done. 

When  a  smith's  forge  is  to  be  used  for  brazing,  use 
a  charcoal  fire,  if  possible.  If  bituminous  coal  must  be 
used,  coke  enough  of  it  to  do  the  work,  as  the  sulphur  in 
the  soft  coal  is  not  conducive  to  good  brazing  any  more 
than  it  is  to  good  welding,  although  a  fair  job  of  brazing 
may  be  done  in  an  ordinary  green  coal  fire  by  letting  the 
coal  remain  without  stirring  while  the  brazing  is  being 
done. 

If  the  work  permits  of  being  readily  handled,  make  a 
sort  of  pit  or  crater  in  the  pile  of  coal  on  the  forge,  and 
blow  a  few  minutes  until  all  the  visible  smoke  and  gas  has 
ceased.  Then  lower  the  work  carefully  into  the  crater 
and  blow  very  lightly,  taking  care  that  the  spelter  is  in 
place  and  that  it  is  not  crowded  away  by  the  melting  of  the 
borax.  Heat  slowly  and  evenly,  allowing  the  fire  to  lie 
without  blast  for  short  intervals.  This  permits  the  work 
to  "soak"  in  the  heat,  as  it  is  called  by  the  workmen,  re- 
sulting in  very  even  heating  of  the  work. 

SK 


Brazing. 

The  workman  should  have  at  hand  a  small  pointed 
rod  or  wire,  with  which  to  poke  into  place  any  bit  of 
spelter  which  may  shift  its  position  and  at  the  instant  of 
melting,  the  spelter  may  be  made  to  flow  quickly  and  in 
the  direction  desired,  by  pressing  the  bits  of  spelter,  one 
at  a  time,  against  the  hot  surface  of  the  work.  A  row  or 
group  of  spelter  granules  seem  a  good  deal  like  sheep. 
Let  one  start  to  run,  and  all  the  others  quickly  follow.  A 
bit  of  spelter  forced  against  the  hot  metal  receives  its  heat 
much  quicker  than  when  lying  loose,  and,  as  soon  as  one 
particle  melts,  it  flows  around  the  others,  permitting  them 
to  receive  heat  and  melt  very  quickly,  hence  the  seeming 
following  in  the  leadership  of  the  first  granule  to  melt. 
The  work  can  be  brazed  at  a  considerable  lower  heat  if  a 
little  care  is  taken  to  start  the  spelter  a-flowing,  as  above 
noted. 

In  brazing  in  the  smith's  forge,  it  is  well  to  hold  the 
work  "high  up,"  that  is,  do  not  let  it  rest  on  the  coal,  but 
keep  it  suspended  between  the  banks  of  incandescent  fuel 
so  that  heat  must  reach  all  parts  by  radiation  instead  of  a 
part  by  convection,  as  would  be  the  case  were  the  work 
to  rest  directly  against  the  hot  coals.  When  large  work  is 
to  be  handled,  of  course  the  above  will  not  apply,  and 
direct  contact  with  the  coal  of  the  part  to  be  brazed  must 
be  prevented  by  the  work  being  supported  at  other  places, 
leaving  the  working  portion  free  and  clear. 

When  considerable  brazing  is  to  be  done,  build  a 
special  furnace  for  that  work  alone,  and,  if  possible,  do 
the  heating  with  gas.  A  blast  of  air  will  be  necessary  but 
a  very  small  blower,  similar  to  that  used  for  a  portable 
forge,  will  do  all  that  is  required.  The  diagram  contained 
in  Fig.  i,  shows  plainly  the  construction  of  a  small  home- 
made furnace  for  brazing.  This  furnace  may  be  built  up 
6 


o 


Brazing. 


Brick  Wall 


t   Fire  Proof  Brick 


Iron 
Plate 


Wooden  Bench 


Brick  Wall 


Gas 

^D 

Air 


Brick  Wai  I 


Air 


Fig.  i.     Home  made  brazing  furnace. 
7 


Brazing. 

on  a  bench  with  loose  bricks,  or  it  may  be  constructed  in  a 
more  permanent  manner,  using  an  iron  shell  with  fire  brick 
lining  instead  of  loose  bricks. 

For  bench  use,  there  is  an  insulating  layer  of  bricks 
laid  upon  the  wood,  then  an  iron  plate  and  then  the  brick 
walls  of  the  furnace  are  laid  up.  It  is  only  necessary  that 
the  bricks  are  sufficient  to  hold  the  flame  around  the  work 
to  be  brazed.  There  is  a  radiation  or  reflection  of  heat 
from  a  hot  incandescent  surface  of  brick  or  other  material, 
like  charcoal  or  carbon,  which  greatly  aids  in  heating  the 
object  to  be  brazed.  In  fact,  it  is  often  impossible  to 
braze  certain  work  with  the  furnace  at  hand,  until  some- 
thing has  been  placed  around  the  work  to  keep  the  heat 
where  it  is  needed — hence  the  use  of  the  confined  space  in 
a  brazing  furnace,  instead  of  letting  the  flame  play  directly 
against  the  work,  in  the  open. 

In  Fig.  I,  the  arrangement  of  the  gas  and  air  pipes  is 
shown.  It  is  necessary  that  the  air  should  be  delivered 
inside  of  the  jet  of  gas,  as  the  air  thus  supplied  inside  the 
gas,  together  with  the  supply  of  air  outside  the  jet,  enables 
a  much  better  and  hotter  flame  to  be  maintained  than 
when  the  air  is  delivered  wholly  around  the  gas  instead  of 
inside  it.  In  the  sketch,  the  two  jets  are  shown  con- 
trolled by  a  single  valve,  each  for  the  air  and  the  gas. 
Should  there  be  trouble  in  obtaining  the  best  results 
with  either  burner,  it  can  be  cured  by  putting  a  valve  in 
each  of  the  four  pipes  leading  to  the  burners.  I'.en  it 
will  be  possible  to  adjust  separately,  the  gas  and  air  supply 
to  each  burner. 

The  entire  piping  may  be  made  up  of  standard  fit- 
tings, as  shown  by  Fig.  I,  or  special  castings  and  forgings 
may  be  provided,  as  desired.  The  size  of  the  furnace  may 
be  made  sufficient  to  take  in  the  usual  work  to  be  brazed, 
8 


Brazing. 

bearing  in  mind  that  the  smaller  the  furnace,  the  less  gas 
will  be  required,  and  the  more  limited  the  work  that  can 
be  done.  On  the  other  hand,  while  the  large  furnace 
costs  more  than  the  small  one,  and  more  piping  and  more 
gas  is  required  to  properly  heat  the  apparatus,  there  is 
always  the  possibility  of  filling  the  large  furnace  with 
bricks  to  fit  it  to  small  work  and  the  gas  can  always  be 
cut  down  to  fit  the  furnace  by  means  of  the  valves  pro- 
vided for  that  purpose.  It  is  in  order,  then,  to  provide  as 
large  a  furnace  as  there  is  likelihood  of  there  being  work 
for,  then  fill  up  the  fire-pot  with  fire  bricks  until  economy 
of  gas  is  secured  for  the  particular  work  to  be  done.  Then, 
when  a  large  piece  of  work  comes  along,  take  out  the 
bricks,  and  a  large  furnace  is  at  hand.  The  above  re- 
marks, of  course,  apply  to  job  and  repair  work.  For 
special  manufacturing  where  the  same  work  is  to  be  done 
day  after  day,  there  will,  of  course,  be  provided  special 
brazing  furnaces,  fitted  for  the  particular  work  in  hand. 

Cleaning  work  which  is  -to  be  brazed,  is  a  most  im- 
portant part  of  the  operation.  Usually,  filing,  scraping  or 
grinding  must  be  resorted  to.  Cleaning  by  means  of  acid 
is  sometimes  attempted,  but  this  method  sometimes  proves 
very  far  from  being  satisfactory.  If  the  surfaces  are  not 
thoroughly  cleaned  of  grease  by  the  use  of  strong  alkali, 
the  acid  will  fail  to  make  the  entire  surface  bright,  and  a 
poor  braze  will  be  the  result.  Again,  if  the  acid  be  not 
entirely  removed  at  the  time  of  cleaning  the  surfaces,  then 
there  will  be  more  trouble,  for  the  acid  remaining  on  the 
metal  will  proceed  to  unite  with  it  into  a  film  of  oxide 
which  will  not  only  prevent  a  perfect  braze,  but  which  will 
probably  cause  an  apparently  perfect  union  to  fall  apart  as 
the  acid  left  in  the  metal  gets  in  its  work  of  undermining 
the  layer  of  brass  which  has  been  put  upon  the  work  dur- 


Brazing. 

ing  the  operation.  Thus :  Free  acid  causes  the  joint  to 
"rust  out" — something  which  is  fatal  to  good  or  lasting 
work. 


The  apparatus  described  above  is  applicable  for  braz- 


7A»  Jerry    Co//aret  Co.  #f. 
Fig.  2.    Gasoline  torch. 

ing  heavy  work.  For  light  brazing,  a  simple  gasoline 
torch  may  be  used,  as  shown  by  Fig.  2.  This  appliance 
gives  a  very  strong  flame,  but  if  it  be  directed  upon  a  piece 
of  iron  for  an  entire  day,  there  would  not  be  sufficient  heat 
to  make  much  of  a  piece  of  iron  red-hot,  to  say  nothing  of 
melting  the  spelter.  However,  there  is  heat  enough  de- 


Brazing. 

veloped  in  the  gasoline  flame  to  make  a  considerable  braze. 
All  that  is  necessary,  is  to  put  the  heat  just  where  it  is 
needed,  and  to  hold  it  there.  This  is  best  done  by  build- 
ing around  the  work  with  charcoal  which  becomes  incan- 
descent from  the  heat  of  the  gasoline  flame,  and  also  sets 
up  a  heating  scheme  from  its  own  combustion. 

If  the  article  to  be  brazed,  be  a  very  small  one,  it  can 
be  placed  bodily  in  a  hole  scooped  in  a  bit  of  charcoal,  as 


Fig.  3.    Brazing  in  charcoal  block. 

shown  by  Fig.  3.  Here  is  shown  the  brazing  of  a  link  in 
a  small  chain.  The  broken  link  is  carefully  wedged  into 
the  hole  in  the  charcoal,  and  bits  of  coal  may  be  packed 
around  the  link  if  the  latter  be  comparatively  large.  The 
place  where  the  link  is  to  be  brazed,  is  indicated  at  a,  and 
the  heat  is  applied  from  the  torch  b,  which,  of  course,  is 
applied  at  the  most  convenient  angle. 

Another  very  convenient  method  of  applying  char- 
coal in  the  brazing  operation,  is  shown  by  Fig.  4.  Here, 
the  work  is  held  between  two  pieces  of  hard  charcoal 


Brazing. 

which  are  clamped  firmly  upon  the  work.  If  the  coal  is 
in  the  way  at  first,  the  flame  from  the  torch  will  quickly 
burn  away  the  interfering  parts.  Two  or  more  pieces  of 
metal  can  be  held  firmly  for  brazing  by  this  method,  and 
the  charcoal  is  also  brought  very  close  to  the  point  of 
heating. 


4.    Another  way  of  using  charcoal. 


A  very  excellent  device  for  brazing  in  a  shop  where 
there  is  considerable  work,  but  no  gas  to  do  it  with,  con- 
sists of  a  pair  of  torch  burners  attached  to  a  compressed 
air  reservoir  of  considerable  size,  as  indicated  by  Fig.  5. 
The  action  of  this  tool  is  the  same  as  for  the  torch ;  it  is 
pumped  up  after  some  gasoline  has  been  put  into  the  air- 
tank,  then  the  burners  are  heated  and  ignited  in  the  usual 
way,  the  necessary  air  pressure  being  pumped  up  in  the 
tank  by  means  of  an  ordinary  bicycle  pump — if  no  better 
way  be  rigged  in  the  shop. 

Pieces  of  fire  brick,  laid  on  either  side  of  the  path  of 


Brazing. 

the  flames  will  confine  them  a  great  deal  and  if  pieces  of 
charcoal  be  placed  inside  of  the  bricks,  a  very  high  degree 
of  heat  can  be  obtained.  Each  torch-head  is  so  arranged 
that  it  can  be  swivelled  in  any  direction.  If  both  torches 
be  turned  so  they  point  nearly  in  the  same  direction,  the 


Fig.  5.    A  good  brazing  device. 


flame  from  the  two  torches  will  form  a  sort  of  V,  and  at 
the  point  where  the  flames  come  together,  is  a  very  hot 
place.  With  a  backing  of  fire  brick  and  charcoal  as  above 
described,  iron  may  almost  be  melted  with  this  appliance. 
Blow-pipe  brazing  is  done  in  exactly  the  same  man- 

13 


Brazing. 

ner  as  described  for  blow-torch  work,  only,  as  large  work 
cannot  be  attempted  as  with  the  torch,  simply  for  the 
reason  that  there  is  not  as  much  heat  developed  with  the 
small  blow-pipe,  as  with  the  larger  blow-torch.  The  in- 
tensity of  the  flame,  however,  is  as  great,  and  even  much 
greater  with  the  little  blow-pipe  than  with  the  largest  torch 
ever  made. 

There  is  an  excellent  tool  for  soldering  and  small 
brazing,  which  consists  of  two  tubes,  one  for  illuminating 
or  hydrogen  gas,  the  other  tube  for  compressed  air.  -These 
tubes  are  attached  to  flexible  rubber  tubes  as  shown  by 
Fig.  6,  one  leading  to  the  gas  fixture,  the  other  to  a  source 


Fig.  6.     A  handy  blow  pipe. 


of  compressed  air.  On  small  work  the  air-tube  is  often, 
held  in  the  mouth  and  the  air  supplied  by  the  operator. 
This  blow-pipe  may  be  attached  to,  and  used  in  connection 
with  the  apparatus  shown  by  Fig.  5.  For  work  larger 
than  the  double  blow-torch  can  handle,  the  air-gas  blow- 
pipe will  be  found  a  very  welcome  addition  to  the  source 
of  heat. 

Fig.  7  illustrates  two  types  of  blow-pipes  ordinarily 
used.  The  ball  on  one  of  them,  is  hollow,  and  is  supposed 
to  render  the  flame  a  little  hotter  by  catching  the  moisture 


Brazing. 

that  may  be  imparted  to  the  air  by  being  blown  through 
the  lungs  and  mouth.  The  chief  benefit  to  be  derived 
from  the  ball,  is  in  catching  whatever  portions  of  saliva 
are  blown  into  the  tube  with  the  air.  The  plain  blow- 
pipe dispenses  with  the  moisture  catching  device,  and 
some  of  the  best  work  is  done  with  this  kind  of  a  blow- 
pipe. 

Fig.  8  shows  the  manner  of  blow-pipe  application  to 
a  small  job  of  brazing.     The  work  is  held  in  a  pair  of 


r/ie  ferry-  Co//ard  Co. 


Fig.  7.    Two  small  blow  pipes. 


tongs  or  pliers,  between  pieces  of  hard  charcoal,  and  the 
flame  of  the  alcohol  lamp  is  diverged  as  shown,  by  the 
stream  of  air  from  the  blow-pipe  nozzle.  For  small  braz- 
ing jobs,  als'o  for  hard  soldering,  and  for  many  kinds  of 
soft-soldering,  this  apparatus  is  of  inestimable  value  to  the 
mechanic.  The  lamp  is  made  with  a  spherical  alcohol 
reservoir,  which  forms  the  body  of  the  lamp,  and  it  swings 
in  any  direction,  in  the  metal  base  of  the  lamp.  The  flame 
may,  therefore,  be  put  in  any  position  within  the  capacity 
of  the  lamp. 

15 


Brazing. 

There  has  recently  developed  two  new  methods  of 
brazing,  which  for  manufacturing  purposes,  throw  in  the 
shade,  all  methods  known  before  the  advent  of  the  two 
methods  in  question,  one  of  which  is  known  as  "Brazing 
by  Immersion,"  and  consists  of  dipping  the  article  to 


Fig.  8.    How  small  blow  pipe 
is  used 


be  brazed,  into  a  bath  of  melted  spelter,  on  top  of  which 
is  maintained  a  body  of  molten  flux,  through  which  the 
articles  to  be  brazed  have  first  to  be  passed.  Fig.  9  shows 
one  form  of  crucible  or  melting  pot  used  to  contain  the 
fluid  flux  and  spelter.  Common  round  crucibles  are  also 
used,  the  only  necessity  being  that  the  containing  vessel 
must  be  large  enough,  and  the  melted  metal  high  enough 
16 


Brazing. 

to  allow  of  the  parts  to  be  brazed  being  immersed  suf- 
ficiently to  bring  them  entirely  beneath  the  surface  of  the 
hot  spelter.  When  the  pot  shown  by  Fig.  9  is  used,  large 
work  is  to  be  handled,  therefore  provision  is  made  for  a 
considerable  body  of  molten  metal,  hence  the  long,  flat 
pot,  into  which  can  be  dipped  almost  any  portion  of  an 
object  which  is  not  absolutely  flat  and  longer  than  the  pot. 
The  position  of  the  work  in  the  pot  is  pretty  well 
shown  by  Fig.  10.  The  pot  is  shown  upon  a  bed  of  coals, 
but  it  would  be  better  if  it  were  heated  by  a  gas  furnace. 


Fig.  9.    Special  crucible  for  immersion. 


On  top  of  the  metal  is  the  body  of  flux,  a,  in  a  molten 
state.  The  body  of  spelter,  b,  underneath  the  flux  is  also 
kept  in  a  melted  state,  and  when  the  object  to  be  brazed 
is  first  introduced,  it  is  held  in  the  hot  flux  for  a  short 
time  before  it  is  put  down  into  the  spelter.  The  object 
of  holding  the  work  a  while  in  the  flux  is  two-fold.  Not 
only  is  the  object  heated,  but  it  is  coated  with  a  layer  of 
flux  which  prevents  oxidation.  When  thoroughly  heated 
and  coated  with  flux,  the  work  is  passed  down  into  the 
spelter,  which  immediately  attaches  itself  to  the  work, 

17 


Brazing. 


coating  every  part  thereof  and  insinuating  itself  into 
every  crack  and  corner.  Between  surfaces,  capillary  at- 
traction fills  all  the  space  and  makes  a  solid  filling  after 
the  work  has  cooled. 

In  this  kind  of  brazing,  parts  of  the  work  which  must 
not  be  adhered  to  by  the  spelter,  are  covered  with  graphite 
specially  prepared  for  the  purpose  in  such  a  manner  that 
the  brass  will  never  adhere  where  the  "anti-flux"  graphite 
has  been  applied.  This  substance  is  made  up  into  a  paste 


Fig.  10.    Using  a  round  crucible. 

and  applied  with  a  brush  to  parts  which  must  not  be 
covered  by. the  spelter.  The  graphite  is  not  affected  by 
the  intense  heat  of  the  spelter,  and  if  care  is  used  in  paint- 
ing on  the  graphite,  little  or  no  filing  will  be  necessary 
after  the  brazing  operation  has  been  finished. 

The  proper  flux  to  use  with  one  of  these  furnaces,  is 
pretty  hard  to  determine.    Some  operators  use  pure  borax, 
and  keep  it  from  three-eighths  of  an  inch,  to  over  two 
18 


Brazing. 

inches  deep  on  top  of  the  spelter,  while  other  people  who 
do  excellent  brazing-,  use  three  parts  boracic  acid  and  one 
part  borax,  while  others  use  exactly  the  opposite  propor- 
tion of  borax  and  acid.  Other  people  use  boracic  acid 
straight,  without  anything  else  with  it.  Again,  some  use 
soda  mixed  with  borax,  and,  in  fact,  almost  any  com- 
pound which  has  borax  in  it,  seems  to  work  well  as  a  flux 
in  the  dipping  process  of  brazing. 

The  other  method  of  brazing,  alluded  to  above,  as 
being  a  great  advance  in  the  process  of  brazing,  is  known 
as  the  "Pich  Process  of  Brazing  Cast  Iron."  Cast  iron 
can  be  brazed  by  the  methods  described  above,  but  it  is 
very  delicate  business,  as  the  iron  melts,  or  at  least  softens 
so  it  will  break  under  the  least  strain,  at  a  temperature 
pretty  near  that  at  which  the  spelter  melts,  so  that  it  is 
almost  impossible  to  melt  the  brass  without  "burning"  up 
the  cast  iron  which  is  being  brazed. 

By  the  Pich  method,  the  surfaces  to  be  brazed  are 
first  brushed  over  with  a  varnish  made  of  oxide  of  copper 
mixed  with  any  liquid  which  will  allow  of  the  copper  being 
spread  with  a  brush,  and  which  will  afterwards  hold  the 
oxide  when  dry. 

After  this  application,  the  brazing  is  carried  out  the 
same  as  in  the  ordinary  method.  The  brass  or  spelter 
is  placed  in  position,  and  the  flux  applied,  then  a  gas-air 
flame  is  applied  as  in  ordinary  brazing.  It  is  assumed 
that  the  metallic  oxide  acts  as  a  reducer  on  the  surface  of 
the  cast  iron  to  be  brazed.  Without  the  oxide,  the  carbon 
above  noted  acts  much  like  the  graphite  used  in  the 
dipping  method  of  brazing  as  an  anti-flux  as  described  in 
the  description  of  the  dipping  process  of  brazing.  It  is 
claimed  that  the  metallic  oxide  is  reduced,  removing  dur- 
ing the  process  of  reduction,  the  carbon  on  the  surface  of 

19 


Soldering. 

the  metal,  and,  it  is  claimed,  often  penetrating  for  a 
distance  of  three  or  four  inches  into  the  metal  itself, 
thereby  making  the  cast  iron  stronger  at  and  near  the 
joint,  than  it  was  before.  Of  this  matter,  the  writer  has 
no  personal  knowledge.  The  process  has  been  described 
very  fully  in  a  paper  by  Wilifred  Lewis,  read  before  the 
American  Society  of  Mechanical  Engineers. 

It  is  claimed  that  both  the  joint  and  the  casting 
itself  is  made  from  5%  to  10%  stronger  by  the  treatment 
with  oxide.  This,  if  correct,  is  a  pointer  of  value  to  the 
iron  worker,  aside  from  in  the  process  of  brazing,  for,  if 
in  certain  cases,  cast  iron  can  have  its  strength  increased 
10%,  it  will  be  of  inestimable  value  to  the  designing 
engineer  to  know  thereof. 


Soldering. 


Soldering  is  much  like  brazing  in  some  of  its  details. 
In  fact,  some  kinds  of  soldering  are  done  exactly  like  some 
kinds  of  brazing,  but  other  varieties  of  soldering  are 
totally  unlike  any  brazing  operations.  Soldering,  there- 
fore, may  be  taken  to  mean  the  uniting  of  two  or  more 
pieces  of  metal,  with  fusible  alloys  of  lead  and  tin.  Some- 
times, lead  areas  are  united  by  melting  their  surfaces 
without  the  use  of  solder,  the  surfaces  being  fluxed.  This 
form  of  soldering  differs  slightly  from  welding,  and  is 
called  "burning"  by  the  trade.  The  method  is  usually  em- 
ployed in  uniting  the  edges  of  sheets  of  lead  used  in  the 
lining  of  acid  tanks  or  similar  apparatus. 

The  particular  kind  of  soldering  usually  employed 
is  by  the  use  of  the  so-called  "soldering  iron,"  which  is 
really  a  copper  bit  placed  on  the  end  of  an  iron  handle. 


Soldering. 

An  alloy  of  lead  and  tin  is  used  which  readily  adheres 
to  the  surface  of  the  bit,  which  must  be  clean,  free  from 
oxide,  etc.  The  operation  of  coating  a  copper  bit  with 
solder  is  known  as  "tinning,"  and  will  be  described  else- 
where. The  theory  of  soft  soldering  is :  that  as  the  soft 
metal  adheres  to,  and  unites  with  the  surface  of  the  copper 
bit,  so  will  the  soft  metal,  under  certain  conditions,  ad- 


r~h«  ferry.  Co//ar-d  Co. 
Figs,  ii  and  xa.  'Forms  of  soldering  "irons. 


here  to,  and  unite  with  the  surface  of  the  metals  to  be 
soldered.  In  fact,  soft  soldering,  as  well  as  brazing,  con- 
sists of  welding  together  two  or  more  pieces  of  similar 
or  dissimilar  metals  by  means  of  another  metal  of  lower 
melting  point.  That  constitutes  soldering  ;  all  the  rest  of 
the  operation,  is  detail,  which  may  be  varied  to  suit  con- 
ditions. 

The  form  of  copper  bit  usually  employed,  is  shown  by 


Soldering. 

Fig.  11,  herewith.  There  are  also  many  other  shapes  in 
common  use,  and  those  represented  by  a,  b,  c  and  d,  in 
Fig.  n,  are  frequently  seen.  In  the  latter  illustration,  a 
is  the  "hatchet"  bit,  used  perhaps  more  frequently  than 
any  of  the  others,  except  that  shown  by  Fig.  n,  which 
is  the  tool  with  which  nearly  all  jobbing  and  repairing 
is  done.  The  "hatchet"  form  of  bit  is  also  shown  by  b, 
Fig.  12,  and  differs  only  that  the  handle  is  swivelled  so 
that  the  edge  of  the  bit  may  be  turned  in  any  direction 
as  made  necessary  by  the  work  in  hand.  This  tool  is  used 
for  long,  straight  seams,  and  for  heavy  work  generally. 
The  bit  shown  at  c,  is  one  of  the  many  shapes  used  for 
special  work.  Tools  of  any  shape  can  be  easily  made  by 
the  workman  who  simply  forges  the  copper  when  cold,  to 
the  size  and  shape  desired.  Copper  forges  on  the  anvil 
pretty  well  and  if  the  precaution  be  taken  to  anneal  the 
bit  frequently,  almost  any  desired  shape  can  be  made  with 
little  if  any  filing  or  cutting — simply  by  forging  alone. 
The  annealing  operation  for  copper,  consists  of  heating  to 
a  dull  red  heat,  and  then  quenching  in  water — the  reverse 
of  the  steel  hardening  operation. 

The  shape  shown  by  C,  is  a  very  useful  tool  where 
soldering  has  to  be  done  in  corners  or  small  places.  It  is 
of  the  same  shape  as  form  A,  except  that  it  is  smaller,  and 
round  in  section,  instead  of  "hex."  The  handle  is  screwed 
into  the  bit,  and  three  holes  are  drilled  and  tapped  so  that 
the  handle  can  be  put  in  as  shown,  or  with  the  flat  end 
either  "hatchet,"  or  "cross,"  as  the  work  to  be  done  may 
demand.  The  swivel  hatchet  bit,  B,  is  one  of  the  most 
useful  tools.  It  ranks  next  to  form  A.  Fitted  with  the 
two  tools,  Fig.  ii,  and  B,  Fig.  12,  all  kinds  of  large 
work  can  be  done.  With  the  addition  of  C,  the  stock  is, 
complete, 

aa 


Soldering. 

Even  more  important  than  the  shape  of  the  bits,  is 
their  condition.  A  man  can  do  good  work  with  any 
"plug"  of  a  tool,  as  long  as  it  is  cleaned  and  well  tinned. 
It  is  in  this,  that  the  life  of  the  tool  lies.  With  a  poorly 
tinned  tool,  it  is  impossible  to  do  good  soldering.  It  is 
then,  of  the  greatest  importance  that  the  user  of  soldering 
tools  knows  how  to  put  them  in  shape  and  how  to  keep 
them  there.  To  begin  with,  a  bit  can  never  remain  in 


Fig.  13,    Brick  "jig"  for  tinning  copper. 

good  condition  if  it  is  over-heated.  Once  a  bit  is  made 
red-hot,  its  usefulness  is  gone  until  it  has  been  re-tinned. 
Heating  in  a  soft  coal  fire  also  causes  the  tinning  to  vanish 
very  quickly. 

In  order  to  learn  how  best  to  keep  a  bit  well  tinned, 
it  is  necessary  to  learn  how  to  tin  the  bit  the  first  time. 
Renewing  the  tinning  is  practically  the  same  as  the  first 
tinning.  To  tin  a  copper,  see  that  it  is  of  the  shape  re- 
quired, then  brighten  the  sides  and  edges  of  the  point 
23 


Soldering. 

with  a  file.  Heat  the  bit  until  it  is  barely  hot  enough  to 
melt  a  little  metal  off  a  stick  of  solder  when  pressed 
against  a  bar  of  that  alloy.  If  the  bit  is  too  hot,  the  tin 
cannot  be  made  to  adhere  to  it.  Cool  the  bit  on  a  wet 
rag,  if  it  should  be  heated  too  hot,  but,  the  sooner  the 
beginner  learns  to  "never  let  the  coppers  get  too  hot,"  the 
sooner  he  will  be  an  expert  at  soldering. 

Perhaps  the  best  "jig"  for  tinning  coppers,  is  a  brick 
with  the  top  cut  out  with  a  cold  chisel,  something  as 
shown  by  Fig.  13.  The  softer  the  brick,  the  better  "jig" 
it  will  make.  A  very  hard  burned  brick  will  not  let  the 
copper  rub  off  little  bits,  while  a  soft,  pale  yellow  brick 


Fig.  14.    A  handy  scraper. 

rubs  off  like  sand  and  the  material  thus  removed,  unites 
with  the  resin  used  in  the  operation,  and  helps  to  brighten 
the  surface  of  the  copper. 

The  cavity  in  the  top  surface  of  the  brick  may  be 
made  about  an  eighth  of  an  inch  deep,  and  some  resin 
melted  into  it.  Some  pieces  of  salammoniac,  scattered  in 
with  the  resin,  improves  the  working  of  the  "jig"  im- 
mensely. In  fact,  that  substance  is  the  natural  flux  for 
copper,  and  that  metal  may  be  soldered  with  no  other 
flux  except  a  little  of  the  muriate  of  ammonia  as  the 
chemical  in  question  is  technically  known.  Some  solder 
is  melted  into  the  cavity  on  top  of  the  brick,  and  there 
mingles  with  the  other  material.  The  heated  copper 


Soldering. 

should  be  rubbed  back  and  forth  on  the  brick,  amid  the 
melted  solder  and  flux.  The  particles  of  brick  serve  to 
brighten  the  copper  so  that  the  solder  readily  adheres, 
covering  the  entire  point  of  the  bit,  as  far  back  as  it  may 
have  been  brightened,  or  rubbed  against  the  surface  of 
the  brick. 

In  using  the  copper  give  it  a  rub  or  two  on  the  brick 
just  before  replacing  to  heat,  and  the  copper  will  always 
keep  well  tinned.  If,  at  any  time,  through  over-heating 
or  soldering  dirty  surfaces,  the  tinning  begins  to  disap- 
pear, a  few  rubs  on  the  brick  will  replace  the  tinning  as 
good  as  new.  When  several  coppers  are  in  use,  they  are 
usually  tinned  by  rubbing  two  bits  together,  taking  one 
with  either  hand,  and  rubbing  them  together  on  the  brick. 
Then,  the  brick  brightens  the  coppers  and  the  rubbing 
of  the  two  together,  causes  the  molten  metal  to  adhere 
very  quickly.  Coppers  may  be  tinned  in  many  other  ways. 
Simply  rubbing  the  bit  on  the  ground,  or  on  the  floor  of 
the  shop  will  brighten  the  metal,  and  the  tinning  may  be 
proceeded  with  on  a  bit  of  tin,  with  nothing  but  resin  and 
solder.  But  the  brick  "jig"  is  much  the  best — and  quick- 
est. 

Overheating  causes  the  copper  to  become  rough  and 
worn  in  spots.  It  often  seems  as  if  an  acid  had  eaten  into 
the  copper  in  one  or  more  places,  but  overheating  is  the 
sole  cause  of  the  trouble.  Learn  to  judge  quickly  and 
correctly  the  degree  of  heat  in  the  copper  by 'holding  the 
bit  about  one  inch  frorh  the  cheek.  The  radiation  of  heat 
is  quickly  felt,  and  in  a  very  short  time  a  man  can  learn 
in  this  way,  to  closely  judge  the  amount  of  heat  in  the 
copper.  The  right  heat  has  been  attained  when  the  solder 
flows  like  water  when  melted  with  the  copper,  on  a  bit  of 
bright  new  tin  plate.  If  the  solder  can  be  made  to  build 
25 


Soldering. 

or  pile  up  in  the  least,  the  copper  is  too  cold.  If  color 
shows  on  that  portion  of  the  copper  which  is  covered  with 
solder,  then  the  bit  is  too  hot.  There  is  quite  a  range  of 
temperature  between  the  two  extremes,  and  there  all  the 
work  of  soldering  should  be  done. 

Never  try  to  solder  when  the  tool  is  so  cold  that  the 
solder  will  not  run  freely.  Good  work  cannot  be  done 
with  the  copper  in  that  condition.  Heat  when  the  solder 
shows  the  least  trace  of  granular  formation,  and  when  it 
begins  to  "build  up"  under  the  copper,  from  the  surface 
of  the  metal  which  is  being  soldered.  If  the  tool  be  a  trifle 
too  hot,  push  it  along  the  top  of  the  brick  "jig"  a  few 
times  and  the  heat  will  be  reduced  and  the  tinning  on  the 
copper  will  be  improved  by  the  operation. 

In  soldering,  the  same  rules  apply  regarding  cleanli- 
ness, as  in  brazing.  The  surface  must  be  free  from  dirt, 
oxide,  or  any  foreign  substance  which  will  prevent  the 
adherence  of  the  solder.  On  old  work,  the  surfaces  must 
be  brightened  by  scraping,  filing  or  rubbing  with  sand- 
paper or  emery  cloth.  Scraping  is  the  best,  and  a  useful 
tool  for  the  purpose  is  shown  by  Fig.  14.  This  scraper 
may  be  bought  from  the  same  dealer  who  supplies  solder- 
ing tools  and  supplies.  This  tool  has  a  steel  blade,  which 
should  be  hardened  and  should  be  ground  on  the  side  not 
shown  in  the  drawing.  The  corners  of  this  tool  are  diffei- 
ent  from  each  other,  one  being  pointed,  the  others  rounded 
off  on  different  radii. 

Where  scraping  can  not  be  done  to  advantage,  filing 
may  be  resorted  to ;  grinding  may  be  done ;  emery  cloth 
used,  or  the  surface  scraped  bright  with  the  blade  of  a 
knife.  The* scratch-brush  may  also  be  used,  but  the  sur- 
faces must  be  cleaned  of  oxide  in  some  manner  at  any 
cost,  or  no  good  soldering  can  be  done. 
26 


Soldering. 

For  all  small  work,  the  solder  should  be  applied  to 
the  copper,  instead  of  direct  to  the  work.  Fig.  15,  illus- 
trates the  proper  method  of  picking  up  solder  with  the  bit. 
A  bar  of  "half  and  half"  is  laid  on  the  bench,  one  end 
being  raised  a  trifle  by  having  a  bit  of  wood,  a  cold 
chisel,  or  some  other  small  article  placed  under  it.  Touch 
the  hot  copper  to  the  bar  of  solder,  and  a  portion  will  melt 
and  adhere  to  the  copper.  If  the  tool  be  held  against  the 


Fig.  16.    Taking  solder  from  bar. 


solder  too  long,  the  solder  will  run  down  upon  the  bench. 
Only  a  very  small  portion  of  the  metal  can  be  taken  up 
at  one  time,  but  the  larger  the  copper,  and  the  tinned 
portion  of  it,  the  more  solder  can  be  taken  up  at  a  time. 
Carry  the  solder  thus  taken  up  to  the  place  to  be  soldered, 
and,  if  the  surfaces  have  b^en  properly  cleaned  and 
fluxed,  the  solder  will  adhere  to  and  run  over  them  like 
water. 

When  very  large  surfaces  have  to  be  soldered,  as  in 
running  seams  in  a  tin  roof,  it  is  necessary  to  melt  the 
solder  on  the  top  of  the  bit  as  that  tool  is  moved  along  the 

27 


Soldering. 

seam.  When  soldering  heavy  lead  pipe,  it  is  necessary 
to  feed  the  solder  in  the  same  manner,  but  for  all  light 
work,  pick  up  the  solder  in  the  manner  described  above. 
If  the  copper  will  not  readily  pick  up  the  solder,  rest  as- 
sured that  the  tool  is  not  in  condition  to  do  good  work, 
and  should  be  sent  at  once  to  the  tinning  brick. 

Heavy  soldering  can  be  done  to  advantage  with  both 
the  soldering  copper  and  the  gasoline  torch  shown  by 
Fig.  2  in  the  brazing  chapter.  For  jobbing,  or  for  small 
work,  the  copper  may  easily  be  heated  by  one  of  these 
convenient  sources  of  heat.  All  that  is  necessary  is  to 
place  the  tool  so  that  the  flame  will  strike  against  the 
copper  bit,  which  may  be  merely  balanced  on  top  of  the 
torch,  upon  lugs  made  for  that  purpose  on  the  torches 
of  the  most  recent  make.  For  heavy  soldering  (occasional 
work),  especially  where  large  pieces  are  to  be  united, 
place  the  torch,  with  the  copper  on  top,  so  that  the  flame 
will  impringe  upon  the  work  after  it  has  passed  the  cop- 
per bit.  Then,  after  the  copper  has  been  sufficiently  heat- 
ed, the  flame  may  be  forced  directly  against  the  work  to 
be  soldered,  the  torch  being  held  in  one  hand,  the  copper 
in  the  other,  and  the  two  worked  in  conjunction.  This 
method  permits  of  a  pretty  heavy  job  being  done  with  a 
light  soldering  bit.  Heat  can  be  put  into  the  copper  as 
well  as  into  the  work,  while  the  soldering  operation  is 
being  carried  on. 

Again,  the  work  may  be  heated  in  the  gasoline  flame, 
then  tinned  with  the  copper.  The  entire  surfaces  to  be 
covered  with  solder  being  given  a  perfect  coating  of 
solder,  the  requisite  flux  and  the  hot  tinned  copper  being 
used  for  this  purpose.  After  this,  the  parts  of  the  work 
may  be  laid  together,  heated  in  the  gas  flame  until  the 
tinning  solder  melts,  then  pressed  together  and  the  neces- 
28 


Soldering. 

sary  additions  of  solder,  smoothing  and  otherwise  placing 
the  solder,  being  done  with  the  copper. 

Another  method  of  soldering  which  is  frequently 
used  in  the  machine  shop,  is  known  as  "sweating."  Per- 
haps two  pieces  of  brass  have  to  be  fastened  together  so  as 
to  leave  an  invisible  joint.  The  workman  will  fit  the  pieces 
as  perfectly  as  possible,  then  he  will  wet  the  parts  to  come 
in  contact,  with  soldering  fluid,  and  place  the  parts  to- 
gether with  a  sheet  of  tin-foil  between.  The  pieces  are 
then  pressed  together  and  wired  or  otherwise  held  fast 
and  heated  until  the  tin-foil  melts.  After  being  allowed 
to  cool,  the  pieces  will  be  found  fastened  together  so 
nicely  that  the  joint  is  imperceptible  to  the  eye  if  good 
fitting  has  been  done. 

Another  process,  also  sometimes  called  "sweating," 
consists  of  tinning  separately  the  parts  to  be  united,  after 
which  they  are  placed  in  contact  with  each  other  and 
firmly  held  in  position  while  being  heated.  After  fusion 
of  the  solder,  the  object  has  its  several  pieces  again 
brought  as  closely  into  contact  as  possible,  either  by  tap- 
ping with  a  hammer,  squeezing  in  a  vise,  by  pressing  to- 
gether by  hand,  or  by  any  means  possible.  Then,  the 
work  is  left  to  cool,  the  superfluous  solder  removed,  and 
a  perfect  solder  joint  is  the  result  provided  the  manipula- 
tions have  all  been  properly  carried  out.  The  method 
last  described  is  commonly  used  in  the  machine  shop  for 
uniting  for  use  during  turning  or  planing  processes,  the 
parts  of  a  ring  or  bushing  which  must  be  in  two  or  more 
pieces  after  completion.  The  several  parts  are  fitted  to- 
gether, sweated  into  a  continuous  ring  and  then  machined, 
after  which  they  are  heated,  whereupon  they  fall  apart 
as  soon  as  the  solder  melts.  The  solder  is  removed,  by 
wiping  the  hot  surfaces  with  a  piece  of  soft  cloth  and  then 
29 


Soldering. 

taking  off  the  balance  of  the  solder  which  is  in  the  shape 
of  a  thin  film,  with  a  scraper. — Not  the  tool  shown  by 
Fig.  14,  but  a  flat  scraper  as  used  by  machinists  on  flat 
work  where  great  truth  of  surface  is  required. 

There  are  several  special  operations  in  soldering, 
where  special  work  has  to  be  done,  and,  in  every  instance, 
the  specials  are  only  adaptations  of  the  ordinary  process 
of  soldering,  to  suit  the  particular  work  to  be  done.  For 
instance :  When  a  number  of  small  or  very  small  parts 
have  to  be  soldered  together  in  such  a  manner  that  the 
soldering  of  one  would  cause  the  others  to  become  un- 
soldered, it  is  customary  to  hold  each  and  every  piece  by 
means  of  clips  and  screws,  or  by  means  of  clamps  or 
weights.  For  some  kinds  of  work,  something  very  differ- 
ent may  be  required  to  hold  all  the  pieces,  and,  in  some 
cases,  it  is  necessary  to  put  the  parts  in  place  one  by  one, 
and  hold  them  there  by  means  of  calcined  plaster,  applied 
in  the  shape  of  cream.  Each  part  is  held  in  position  until 
the  plaster  sets,  after  which  they  each  will  stay  in  place 
until  the  solder  can  be  applied. 

For  small  work,  which  has  to  be  thus  held  in  place, 
the  soldering  copper  is  frequently  too  large  to  get  into  the 
small  corners  between  the  several  parts,  and  a  good  deal 
of  trouble  is  frequently  met  with  in  getting  the  solder 
properly  distributed.  For  work  of  this  kind,  the  blow- 
pipe is  the  most  desirable  tool.  The  blow-torch  may  be 
substituted  for  the  blow-pipe  if  desired,  but  the  former 
tool  enables  the  heat  to  be  localized  better  than  with  the 
torch.  In  either  case,  apply  the  heat  until  the  solder 
flows  readily,  then  with  a  short  bit  of  copper  wire,  fastened 
to  the  end  of  an  iron  wire  handle,  the  solder  may  readily 
be  made  to  flow  where  it  is  needed. 

If  the  bit  of  thick  copper  wire  on  the  end  of  an  iron 
30 


Soldering. 

wire  handle  is  not  at  hand,  a  piece  of  copper  wire  may  be 
used  with  good  results  to  poke  the  solder  around  into  the 
joints,  but  the  trouble  with  the  solid  copper  wire  is  that 
copper  is  a  much  better  conductor  of  heat  than  the  iron 
and  the  solid  copper  wire  used  as  a  small  soldering  bit, 
speedily  becomes  hot  along  its  entire  length  and  in  so 
doing  takes  eo  much  heat  away  from  the  business  end  of 
the  tool  that  it  will  not  continue  to  melt  the  solder. 

The  value  of  a  soldering  job  frequently  depends  upon 
the  use  of  a  proper  soldering  fluid,  and  the  stability  of 
the  soldered  joint  often  depends  -largely  thereupon.  When 
acid  is  used  there  is  little  possibility  that  the  joint  wilV 
be  permanent,  unless  means  are  taken  for  removing  the 
excess  of  acid.  However,  this  matter  is  much  of  a  puz- 
zle to  some  very  advanced  engineers,  some  acid  soldered 
joints  lasting  apparently  as  long  as  those  soldered  with- 
out the  use  of  acid,  other  acid  soldered  joints  coming  to 
pieces  very  quickly  after  their  making.  The  electrical 
people  have  solved  the  question  of  the  durability  of  the 
acid  soldering  joint  by  prohibiting  its  use  entirely  in  elec- 
trical work. 

One  of  the  most  handy  soldering  solutions  consists 
of  common  resin  dissolved  in  alcohol.  This  preparation 
makes  a  sort  of  varnish,  which,  when  applied  to  a  sur- 
face, soon  parts  with  its  alcohol,  leaving  a  thin  film  of 
resin  exactly  where  it  will  do  the  most  good  in  soldering. 
Some  good  soldering  solutions  have  borax  dissolved  in 
them;  others  have  some  salammoniac  (muriate  of  am- 
monia) among  their  ingredients.  This  substance  is  the 
natural  flux  for  copper,  and,  owing  to  the  presence  of 
that  metal  in  brass,  it  works  pretty  well  in  fluxing  that 
alloy  for  soldering. 

The  most  common  method  of  applying  resin  in  soi- 

31 


Soldering. 

dering  is  to  powder  that  material  and  apply  it  to  the 
work  by  means  of  a  swab  consisting  of  a  small  tin  or 
wooden  handle  to  which  a  tuft  of  cotton  or  a  few  folds 
of  cloth  have  been  fastened.  An  ordinary  coffee  mill  is 
a  desirable  machine  for  pulverizing-  resin,  also  for  borax. 
In  the  dry  flux  salammoniac  may  be  ground  up  with  the 
resin  in  almost  any  proportion  from  one  of  salammoniac 
to  one  hundred  of  resin  up.  In  the  liquid  solution,  the 
proportions  may  be  the  same,  provided  a  liquid  can  be 
found  which  will  carry  both  the  resin  and  the  salam- 
moniac. A  solution  of  salammoniac  and  borax,  or  boracic 
acid,  is  much  valued  by  some  mechanics  as  a  soldering 
fluid. 

Several  ancient  receipts  for  soldering  fluids  or  acids 
call  for  "killed  spirits  of  salt."  Chemically,  the  solution 
is  one  of  muriate  of  zinc.  It  may  be  readily  prepared,  as 
follows:  Place  three  parts  of  hydrochloric  (muriatic) 
acid  and  one  part  water  in  a  lead,  glass  or  wooden  ves- 
sel, then  add  pieces  of  zinc  as  long  as  any  action  of  the 
acid  upon  the  zinc,  can  be  seen.  Some  zinc  remaining 
undissolved  in  the  solution  after  standing  for  several 
hours  is  proof  that  no  more  zinc  will  be  dissolved  by  the 
acid.  Before  declaring  the  operation  completed,  the  fol- 
lowing test  should  be  made  to  determine  that  there  is  suf- 
ficient water  in  the  solution,  without  which  the  maximum 
quantity  of  zinc  will  not  be  dissolved  by  the  acid.  To 
make  this  test,  remove  a  few  drops  of  the  solution  to  a 
clean  vessel  and  place  a  bit  of  clean  zinc  in  the  liquid. 
Add  water  drop  by  drop,  and  observe  if  any  action  upon 
the  zinc  follows  the  addition  of  water  to  the  solution. 
If  such  action  commences,  water  should  be  added  to  the 
bulk  of  the  solution  until  further  addition  does  not  have 
effect  upon  the  zinc.  If,  however,  no  action  is  observed 
32 


Soldering. 

in  the  test  solution,  the  process  may  be  declared  finished, 
and  the  main  solution  should  be  allowed  to  settle,  after 
which  the  clear  portion  is  carefully  poured  off.  The 
sediment,  consisting  of  zinc  oxide  and  perhaps  impurities 
contained  in  that  metal,  is  not  desirable  in  a  working  solu- 
tion for  soldering.  True,  work  can  be  done  with  dirty 
soldering  acid  or  other  fluid,  but  better  work  can  be  done 
with  clean  solutions,  as  well  as  surfaces,  and  tools. 


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